Engine cooling system



` Feb. 1s, 1936.

A. L. MaccLAxN 2,031,541

'ENGINE COOLING SYSTEM Filed July 8, 1952 2 Sheets-Sheet l INVENTUI? ALBEE'T vI Ew/S MHC CLA/N.

Feb. 1s, 1936. A. L, MaCCLAIN 2,031,541

ENGINE'cooLING SYSTEM Filed July 8, 1932 2 Sheets-Sheet 2 Patented Feb. 18, 1936 n UNITED STATES ENGINE COOLING `SYSTEM Albert Lewis MacClain, Manchester, Conn., assignor,.by mesne assignments, to United Aircraft Corporation, a corporation of Delaware Application Iuly 8, 1932, Serial No. 621,425

s claims. (o1. 12a-171) invention relates to an improvement in aircooled internal combustion engines and is shown applied on a type of engine adapted to be used in aircraft.

It has been found that as the power output of internal combustion engines is increased and these engines encased in cowls to reduce their air resistance the diiliculty of properly cooling the engine is likewise increased and especially is this true of multiple row aircooled engines. A point is finally reached at which the conventional structures do not provide suillcient cooling.

An` object of this invention is to provide means to assist in cooling internal combustion engines.

Further and other objects and advantages will be apparent from the specification and claims and from the accompanying drawings which illustrate what is now considered the' preferred embodiment.

Figure 1 is a partial front elevation of the engine partly in section and with certain of the cylinders and other parts removed to better show the baille structure.

Figure 2 is a developed section showing one front and two rear cylinders..

Figure 3 is a diagrammatic side view partly in section with many'of the engine parts omitted.

Figure 4 is a developed section showing two front and one rear cylinder with a modified form of baille retainer. l Figure 1 shows a radial engine of the aircooled type having a crankcase I6, a propeller hub I8 and 14 cylinders indicated by numerals I to I4 inclusive. Cylinders I, 2, I2 and I4 have been omitted to more clearly show the air deiiecting means. A cowl, 20, of any suitable type surrounds the engine. 'I'his cowl is preferably of the type called low drag cowls and which is adapted to reduce the drag of the engine. This cowl is also preferably of the one piece split type in which the ring forming the cowl is split from the front to the rear edge and drawn together by means of turn buckles which draw the cowl tightly onto the felt pads 22, which are placed between the cowl and the rocker box covers, thus holding the cowl in place'on the engine. In the embodi-v ment shown the cowl isopen at the front and rear but if desired a. perforated nose' cowl may be used to partially close the front of the ring cowl.

It has been found that even if as much air as possible is allowedto pass under the/cowl and around and between the engine cylinders there may be times during which the temperature of the engine may rise beyond desirable limits. If, however, the air flow is restricted as by placing baflles between the cylinders and between the rocker boxes it has been found that a material improvement in the cooling results.

It has also been found that this restricted air-v ow in addition to giving a material improvement in the cooling also increases the airplane speed. 'I'his increase in speedis probably due to a reduction in the drag of the engine and cowl.

In the embodiment shown in the drawings'bafiles 24 and 26 are placed between the cylinders thereby blocking the space between the front and rear cylinders except for the space between the individual cooling fins. These bailles are made V shaped and follow the contour of the voutside edges of the iins as closely as practicable. They also extend to a lpoint as close to the crankcase of the engine as is practicable and they may extend to thecowl but in order to make the rocker boxes more accessible for adjustments when the cowl is removed the bailles may stop short of the cowl and join bales 32 and 34 which are fastened to the cowl and in effect, form extensions of the ballles 24 and 26. 'I'he bales 24,` 26, y3 2 and 34 thus form deilectors which close the space between Vthe cylinders as nearly as is practicable.

The baille 24 is.held in place in the modification shown in Figures l and 2, by means of a bolt 3S, which passes through a suitable hole in the baille and is connected with a spring 40. By tightening the wing nut 38 the baille and the spring 40 are drawn toward each other and securely wedged between the two cylinders. The baffles are provided with the bosses 42 which bear on the cylinder fins and which bring the point of support of the bailles far enough around on the cylinder fins 3 so that expansion and contraction of the cylinder or baille will not cause the baille to be tightly wedged between the cylinders and perhaps force them apart. If any such action should attempt to take place the supports 42 would slide on the engine hns and perhaps create a little change in the tension of the spring 40 which acts as a sort of a at spring. 'I'he supports 42 may rest onA the outside edges of the ns as shown in Figure 2, in

which case the contour of the outside of the ilns prevents longitudinal movement of the baille, or they may be shaped to fit between two of the ns. The spring 4|)` is formed from a piece of round spring wire in the embodiment shown but obviously may take other forms.

In the form of engine illustrated a considerable space exists between the rocker boxes on each individual engine. In order to prevent a free passage of air through this space the V shaped baflles 28 and 30 are disposed therein and connected with the cowl. These bailles might be flat plates formed with the proper contour but are illustrated as a sheet of metal formed into a V shape trough and tapered to a point toward the front of the cowl. y

Figure 4 shows a modification of the means for holding the bailles between the cylinders and comprises a turnbuckle 44 connected with the baille 24 at 46 and with the baille 26 at 48. The turnbuckle 44 is adapted to force the points 46 and 48 apart and thus force `the bames 24 and 26 to their position between the cylinders. The bailies are otherwise similar to those shown in Figure 2.

The head baiiies and the intercylinder bailies in eiect form a partition which separates the engine and cowl into a front section and a rear section. Due to movement of the engine and cowl through the air or to the propeller thrust or both it appears probable that increased pressure is created in the front section and a reduced pressure is created in the rear section of the engine and cowl. 'I'his increased pressure difference rcauses an increase in the velocity of the air over the fins and probably causes a greater rate of heat exchange, although the quantity of air that is passed under the cowl and through the engine is probably less than that in an engine not provided with the bailies.

The installation of the pressure bailles reduces the quantity of air flowing through the cowl and thereby permits the luse of a ring cowl of improved stream line shape having an air inlet opening and an air outlet opening of less extent than the ring cowls used on unballled engines. The reduction in the air inlet opening permits a more pronounced curvature and improved air flow at the nose of the cowl and the reductionv in the outlet opening eliminates a large portion of the eddy currents and tl'bulence at the cowl trailing edge. This improved cowl shape is an important factor in reducing the drag of the cowled engine.

It is to be understood that the invention is not limited to the specific embodiment herein illustrated and described but may be used in other ways without departure from its spirit as dened by the following claims.

I claim: l

1. Means for decreasing the drag of an aircooled radial engine having heat4 radiating fins and increasing its heat radiating properties comprising a cowl of substantially ring form enclosing the entire nned area of said engineand extending with diminishing size in the direction of travel of said engine said cowl being open in front and in back, and bailles between the cylinders of said engine, substantially completely closing the space between said cylindersexcept between the individual cooling fins.v

2. In a multicylinder aircraft engine of the aircooled radial type, having the cylinders arranged in two parallel planes with the cylinders of one plane arranged between the cylinders of the other plane, said cylinders having heat radiating ns, a cowling of substantially ring form arranged to completely encircle said engine, a plurality oi' bames mounted on said engine to form with said 'engine a partition ln said cowl, so that the air forced under said cowl by relative motion of the engine and the surrounding air is forced to pass between individual cooling ilns in passing from one side of the partition to the other.

3. A radial engine, comprising a plurality of cylinders radiallyv arranged around a common center line with some of the cylinders axially spaced from others, a drag reducing ring cowl arranged around the entire group of cylinders, fins on the cylinders, means for further reducing the drag of said engine and cowl comprising bailies arranged between said cylinders, said baiiies following substantially the contour defined by outermostv portions of said engine fins so as to substantially close the space between the cylinders except the space between the individual fins.

4. Means for holding baliies in position between the cylinders of a multicylinder engine having cylinders arranged in a plurality of parallel planes comprising in combination baliles having portions contacting with the engine, a toggle fastened at one end to one baille and at the other end to another bame and adapted to force the baiiles apart and into place between the cylinders. i

5. Means for holding bailles in position between the cylinders of a multicylinder engine having cylinders arranged in a plurality of parallel planes comprising, in combination, baiiles having portions contacting with the engine, means between two of the bailles adapted to separate the ballles and urge them into position between the cylinders.

6. Means for decreasing the drag of an aircooled radial engine having heat radiating fins, which comprises a drag reducing cowl of substantially ring form openat the front andV rear and encircling the engine, kand means substantially completely blocking the passage of air past said engine under the cowl except between the individual heat radiating fins.

7. Means for decreasing the drag of a radial air-cooled engine having a propeller rotating adjacent thereto which comprises a non-rotatable cowl of substantially ring. form encircling the entire finned area of said engine with the leading edge of said cowl in front of lthe engine cylinders, said cowl being open at the front and rear, one of said openings being between the propeller and the-engine, bames adjacent the engine cylinders adapted to restrict the passage of air under said cowl substantially to the cross-sectional area between the cooling fins of each cylinder, said bailies acting to increase the pressure difference between the front and rear of said cylinders created by relative motion of the cowl encircled engine and the surrounding air.

8. Means i'or decreasing the drag of a radial air-cooled engine having a propeller rotating adjacent thereto which comprises, a stream line cowl of ring form ixed to said engine and entirely enclosing the nned area thereof with the leading edge of said cowl in front of the cylinders of said engine, said cowl having a rear opening and having a front opening between said engine and said propeller adjacent to .the hub of said propeller, and baiiies adjacent to the engine cylinders extending from the interior surface of said cowl to said engine and between adjacent surfaces of said cylinders to restrict the passage of air through said cowl to the air flowing between adjacent cooling flns on said cylinders, to bring the air entering the front opening of said cowl to a substantial standstill with respect to said cowl to provide an air pressure reservoir which distributes cooling air equally to all of said cooling ilns and guides external air smoothly yover vthe nose of said cowl.

ALBERT LEWIS MAcCLAIN. 

